Continuous positive airway pressure therapy, or CPAP, helps patients with sleep apnea breathe better during sleep by pushing air into the nose through a mask to keep airways open.

The treatment has been shown to improve daytime sleepiness and reduce blood pressure, but its impact on heart disease, stroke, and diabetes risk factors that are common in patients with sleep apnea has not been well understood.

Results from a study published in the Dec. 15 issue of the New England Journal of Medicine suggest that CPAP is associated with a lower risk for metabolic syndrome, a cluster of symptoms that increase the risk for heart disease, stroke, and diabetes.

Researcher Surendra K. Sharma, MD, PhD, of the All India Institute of Medical Sciences in New Delhi tells WebMD that along with weight loss and lifestyle modification, treatment with CPAP may be an important way to lower heart attack, stroke, and diabetes risk in patients with sleep apnea.

Sleep Apnea, CPAP, and the Heart

More than 18 million adults in the U.S. have sleep apnea, according to the National Sleep Foundation, and a significant percentage of them are overweight or obese.

Other than weight loss, CPAP is considered the most effective nonsurgical treatment for patients with moderate to severe sleep apnea.

The new study included 86 patients with sleep apnea, including 75 who had metabolic syndrome.

Study participants were treated with either CPAP or a fake therapy for three months, followed by a month of no treatment and three additional months of the opposite treatment.

Before and after each phase of the study, researchers recorded the participants’ blood pressure, blood sugar, blood fats called triglycerides, hemoglobin A1c levels, neck artery thickness, abdominal fat, and insulin resistance, which measures the body's ability to use insulin efficiently.

When compared to the fake therapy, three months on CPAP was associated with significantly lower blood pressure, total cholesterol, triglycerides, and LDL cholesterol, the so-called bad cholesterol.

Treatment with CPAP was also associated with a significant decrease in abdominal fat and body mass index (BMI).

It was also associated with a significant decrease in hemoglobin A1c values, which indicate average blood sugar levels over the past two to three months. And 1 in 5 patients with metabolic syndrome before starting CPAP treatment no longer had the condition after three months of treatment.

Lack of Sleep and Chronic Disease

Sleep specialist Meir Kryger, MD, of the Yale University School of Medicine and the VA Connecticut Health System, tells WebMD the findings highlight the growing recognition that sleep disturbances play a significant role in chronic disease.

Kryger is a board member with the National Sleep Foundation.

“It is now clear that patients with heart disease or a metabolic disease like type 2 diabetes should be asked about their sleep habits, and they should be treated if they have sleep apnea,” he says.

Cardiologist Tara Narula, MD, of Lenox Hill Hospital in New York City, says sleep issues have not been a major focus in cardiology in the past. But she says this is changing.

“We are seeing more and more studies linking sleep disorders and stress to [heart disease and stroke risk],” she tells WebMD. “This study suggests that a simple, effective treatment for sleep apnea may help reverse the abnormalities that lead to heart attack and stroke.”

While CPAP may be simple and effective, Kryger acknowledges that most patients don’t like wearing a mask while they sleep.

But he adds that CPAP technology and masks have improved dramatically over the last few years. Most new machines are even able to monitor how often the treatment is used and how well it is working.